Field
The present invention relates to a membrane electrode assembly and a fuel cell including the membrane electrode assembly.
Related Art
A fuel cell includes a membrane electrode assembly configured by stacking a catalyst layer and a gas diffusion layer in this sequence on each surface of an electrolyte membrane. As described in JP 2010-251140A, one proposed technique uses a catalyst layer divided into a first layer portion that is in contact with the electrolyte membrane, a second layer portion that is in contact with the gas diffusion layer and a third layer portion that is located between the first layer portion and the second layer portion, and sets amounts of ionomer in the first layer portion and the second layer portion to be larger than an amount of ionomer in the third layer portion. This reduces the transfer resistance of hydrogen ion (H+, also called “proton”), enhances the gas diffusibility, and additionally prevents a decrease in water content in the electrolyte membrane and the catalyst layer.